#!/usr/bin/perl -w

use strict;

die "$0: VALUE MIN MAX\n"  if @ARGV != 3;
my ($key, $min, $max) = @ARGV;
die "Erstes Argument muss [a-d] sein!\n"  unless $key =~ m/^[a-d]$/i;
$key = lc $key;

open LISTE, "<", "liste.txt"  or  die $!;
while ( <LISTE> )
{
    if ( m/$key=(\d+)/o   &&   $1 >= $min   &&   $1<= $max )
    {
        print;
    }
}
close LISTE;